Tracking energy consumption using a boost-buck technique

ABSTRACT

The invention relates to an apparatus and method for tracking energy consumption. An energy tracking system comprises at least one switching element, at least one inductor and a control block to keep the output voltage at a pre-selected level. The switching elements are configured to apply the source of energy to the inductors. The control block compares the output voltage of the energy tracking system to a reference value and controls the switching of the switched elements in order to transfer energy for the primary voltage into a secondary voltage at the output of the energy tracking system. The electronic device further comprises an ON-time and OFF-time generator and an accumulator wherein the control block is coupled to receive a signal from the ON-time and OFF-time generator and generates switching signals for the at least one switching element in the form of ON-time pulses with a constant width ON-time.

This application is a continuation of U.S. patent application Ser. No.14/987,527, filed Jan. 4, 2016, which is a continuation of U.S. patentapplication Ser. No. 13/874,608, filed May 1, 2013, both of which areincorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The invention relates to an electronic device and a method for trackingthe energy consumption, and more specifically to an electronic deviceand a method for determining energy consumption using the principle ofstoring energy in an inductor and transferring the energy into outputenergy storing components.

The present application relates to jointly owned U.S. Patent Applicationcorresponding to application Ser. No. 13/329,073 entitled, “ElectronicDevice and Method for Power Measurement.”

BACKGROUND

Reducing energy consumption is important in the development andimprovement of electronic devices, in particular if they are mobile orportable electronic devices. In order to save energy, electronic devicesare more and more controlled by sophisticated schemes in which themagnitude of the consumed currents varies over several decades ofmagnitude. In low power modes some hundreds of nA (nano-amperes) of acurrent may be consumed while other operation modes require up toseveral hundreds of mA (milli-amperes). It is often necessary to measurethese currents over a wide range (e.g. from nano-amperes tomilli-amperes) with an acceptable accuracy while at the same time beingable to track highly dynamic current changes. Furthermore, any sideeffects due to measuring the consumed energy should be avoided or wellcontrolled. For example, it is preferred that an increase of the energyconsumption due to the energy measurement itself not occur.

One of the more common techniques for measuring a current is ameasurement using a shunt device or a shunt resister. Using a shuntdevice for the power measurement requires very high precision analogueto digital converters in order to cover the full dynamic range of thepossible magnitudes of the currents. For example, when four and a halfdecades of measurement with one percent precision is required, a24-Bit-converter would be required. Furthermore, shunt devices generatea voltage drop. This voltage should be compensated, while thecompensation circuitry constitutes a potential source of errors. Directload compensation can be difficult. This means that the measurementrange and therefore the circuitry used for measuring the powerconsumption has to be adapted during the energy measurement procedure.This increases complexity and entails more potential errors.

Still further, measuring a current indirectly by measuring the voltageacross a shunt device requires an initial voltage change on the target.If a buffer capacitor is coupled to the target side (output side of anenergy transfer circuits), the buffer capacitor delivers currentimmediately and needs to be recharged. This behavior affects the truecurrent response of the device under test. Another approach of measuringthe energy consumption employs a current mirror. One side of the currentmirror delivers the current to the target including the targetcapacitor. The other side of the current mirror is coupled to an Amperemeter to which the mirrored current is fed. This approach has theadvantage that the distortion caused by the target capacitor isminimized. However, the required pairing of the power and sense fieldeffect transistors (FET) is rather poor and is not capable of trackingthe huge current magnitude to be supported.

SUMMARY

It is an object of the invention to provide an electronic device 200 anda method for measuring energy consumption in an energy consuming systemthat covers a large range of magnitudes of supply currents, high dynamiccurrent changes and does not affect the basic functionality of thecircuit which energy consumption is measured. According to an aspect ofthe invention, an electronic device 200 is provided that comprisesswitched mode energy tracking circuitry. The switched mode circuitrycomprises one or more switching elements SWA-SWB, SW1 a-SW1 b andSWia-SWib, one or more in inductors, LA-Li, a capacitor CA and comparecircuits 406 and 434 that control the output voltage level VO and theoutput voltage level V1 respectively. The switching elements, SWA-SWia,are configured to switch current through the inductors LA-Lirespectively. The switches, SWA-SWB, SW1 a-SW1 ia and SW1 b-SW1 ib, maybe transistors. The voltage compare circuits 406 and 434 may be erroramplifiers, a voltage comparators, or an A/D converters which conversionresult is compared to a reference voltage VL(ref). The ON/OFF generator408 is configured to control the ON-time and OFF-time of the switchingelements, SW1 a-SW1 ia and SW1 b-SW1 ib, in order to transfer energyfrom a primary energy source, e.g. power supply, to the output VO of theenergy tracking system and to control the level of the output voltageVO. The electronic device 200 further comprises control logic stagesCNTLA, CNTL1 and CTNLi. A control block 410 comprises an error handlingblock 420, reporting block 416, a calibration block 428, an accumulator430 of the individual ON-time events, a sequencing block 422, a rangecontrol block 418 and a demand control block 424.

The control logic stages CTNLA-CNTLi generate the switching signalsSWSA, SWS1 a to SWSib for the switched transistors, SWA-SWB, SW1 a-SW1ia and SW1 b-SW1 ib, in the form of ON-time pulses with a constant widthON-time. The control logic stages, CTNLA-CNTLi, also control theOFF-time which is used also as an indicator of the energy in theinductors that is transferred to the output VO. The voltage-comparecircuits 406 and 432 flag when the next ON-time pulse has to begenerated. If the OFF-time is not over before the next ON-time istriggered, the system reports an error condition. An error condition isalso reported if the output voltage VL is not within predefined limits.

The switching signals, SWS1 a to SWSib, are formed according to a pulsedensity scheme. The highest density of pulses occurs when the On-timeand OFF-time are met at the time another ON-time is requested. Higherdensity is enabled by default or by control information (e.g. a controlbit and this is handled by the control circuit as described previously).In an embodiment of the invention, the pulse accumulator 430 can be inthe simplest implementation a digital counter. The counter in thisembodiment is then configured to count the number of ON-time pulses fordetermining the consumed power based on the number of ON-time pulses pertime. The constant pulse width of the ON-time pulses makes the influenceof the system components such as the non-linear behavior of switchedtransistors or inductors negligible. The target voltage offset at theoutput of the energy tracking system is highly reduced. A wide range ofmagnitudes of the measured current can be covered.

According to another aspect of the invention, the electronic devicecomprises a first capacitor C1 coupled to the input of the energytracking system, a second capacitor CA at the input of the energytracking blocks 204 and 206 and a third capacitor C2 coupled to theoutput of the energy tracking system. The ON-time of the switchingelement in conjunction with the inductor's L1 value and the value of thecapacitor CA is configured to keep the voltage within the systemaccuracy requirements. The output capacitor C2 is of such value that thevoltage increase during transferring the energy from the inductor L1 toLi is within the accuracy expectations.

The energy tracking system of this embodiment is contrary to a pulsewidth modulation scheme and nearly all energy in the inductors, L1-Lican be transferred to capacitor C2. The frequency of the ON-time pulsesis proportional to and practically a linear function of the consumedcurrent. During a settled operation condition, in which the input andoutput voltages and the charges on the input and output capacitors havesettled, each ON-time pulse of the switched transfers about the sameamount of energy.

According to another embodiment of the invention, a reference impedance205 or a reference resistor R can be coupled to the output of the energytracking system in order to make a reference energy measurement. Theresults of the reference measurement(s) can then be used for calibratingthe system to the energy consumption. Therefore, the number of theON-time pulses can be used for determining the energy consumption duringnormal operation even with an unknown load (e.g. C3 & Z). The unknownload according to an embodiment of the invention can be an electronicdevice.

In an embodiment of the invention, the electronic device 200 comprisesan energy tracking system with switching components SWA-SWB, SW1 a-SW1ia and SW1 b-SW1 ib, inductors LA, L1, Li, transfer support diodesDA-Di. The switching components SWA-SW1 ia can then be configured toenable current through the inductors LA-Li respectively. The optionalswitches SWB-SWib may be used to conduct current during the OFF-time tosupport the transfer of energy from an inductor to the output. Theoptional switch SWB does not conduct energy after the energy transfer iscompleted preventing that energy from flowing back from the output tothe input. The optional switches SW1 b-SWib do not conduct energy afterthe energy transfer is completed preventing that energy from flowingfrom the output to ground. The voltage compare circuits 406 and 434 canbe error comparators or error amplifiers. The voltage compare circuit406 is configured to send a signal 426 to the control circuit 410 andthe ON/OFF generator 408 so that the switching components SW1 a-SW1 iaand SW1 b-SW1 ib can be triggered or be prepared to be triggered. Thecompare circuits 406 and 434 serve to deliver the demand on energy tomaintain a stable output voltage VO and V1 respectively. The generationand frequency of the ON-time pulses can be controlled in response to achange of the output voltages VO. The ON-time pulses can be combinedwith a time stamp on an individual basis or on a group of pulses.

Another embodiment of the invention includes ON-time pulses that arebased on a defined time and the difference to that defined time base isbounded by pulses or a group of pulses. The energy consumption may thenbe determined based on the number of the ON-time pulses per consideredtime period.

In an aspect of the invention, the energy consumption may then bederived from a phase variation of the ON-time pulses. This aspect allowsa quick evaluation of changes of the power consumption. The energytransfer during ON-time pulses usually is significantly smaller than theenergy stored on a second capacitor CA coupled to the input of theenergy transfer system. The energy withdrawn from the energy source atthe input of the energy transfer system influences the energytransferred during the ON-time. The influence of the energy sourcingcapability is a factor in the calibration cycle.

The energy stored on a second capacitor C2 coupled to the output of theenergy transfer system is also significantly larger than the energystored in the inductor during the ON-time and transferred to the outputand the capacitor C2 during OFF-time. The energy consumption may becalibrated by coupling one or more reference impedances 205 to theoutput of the energy transfer system. The result of the calibration maythen be used for normalizing the energy consumption during normaloperation. During normal operation a target device or a device undertest (DUT) 208 is then coupled to the output of the energy transfersystem instead of the reference impedance 205. However, in anotherembodiment, the reference impedance 205 may be coupled to the outputwhile the target load device or DUT 208 is still coupled to the output.The energy of one or a group of ON-time pulses due to the additionalload of the reference load can be evaluated for calibrating the powermeasurement based on the energy pulse ON-time and OFF-time conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a circuit measuring the current, the voltage and the timingrelations to calculate the energy consumed within the load of thedevice-under-test. (Prior Art)

FIG. 2a is a simplified circuit diagram of an embodiment of theinvention.

FIGS. 2b and 2c are simplified circuit diagrams of an embodiment of theinvention.

FIG. 3 is a diagram showing waveforms of signals of the circuit shown inFIG. 2a according to an embodiment of the invention.

FIG. 4 is a circuit diagram of an embodiment of the invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 shows a circuit 101 that measures the load current via avoltage-to-voltage converter 102, an A/D converter 104 and timer 106.The energy EL used by the load is calculated in block EL 108. Thevoltage VL is measured via the A/D converter 104. When the A/D converter104 is used for sequential conversions, phase related errors may occur.A timer 106 is used to create the time base t(b) for the A/D converter104. The energy EL used by the load (i.e. DUT) is calculated by theblock EL according to equation 1 below.

ELx=IL*VL*t(b)  Equation 1

-   -   where x={1 . . . i}

FIG. 2a shows a simplified diagram of an embodiment of the invention. Inthis embodiment, an energy tracking system 200 comprises energy transferblocks 202, 204, 206, a control circuit 201 and reference impedance 205.In this embodiment of the invention, energy transfer block 202 is a“boost” circuit that comprises switched transistors SWA and SWB, diodeDA, capacitor CA and inductor LA. In this embodiment of the invention,energy transfer blocks 204 and 206 are “buck” circuits. Energy transferblock 204 comprises switched transistors SW1 a and SW1 b, diode D1, andinductor L1. Energy transfer block 206 comprises switched transistorsSWia and SWib, diode Di, and inductor Li. In this example two buckenergy transfer blocks 204 and 206 are shown. However, more than twobuck energy transfer blocks may be used.

In boost block 202, one terminal of inductor LA is coupled to a firstswitched transistor SWA, a second switched transistor SWB and to theanode of diode DA. The other terminal of the inductor LA is coupled toan input of the energy transfer block 202. The cathode of the diode DA,a terminal of the capacitor CA and a terminal of the second switchedtransistor SWB are connected to an output of the boost block 202. Aterminal of the capacitor CA and a terminal of the first switchedtransistor SWA are connected to ground. The switched transistors SWA andSWB can be referred to as energizing switches. The diode DA may bereplaced or complemented by the second switch SWB. The control circuit201 controls the energy switches SWSA and SWSB. A function of boostblock 202 is to transfer or “boost” the voltage on the input to a highervoltage level in order to have enough voltage margin for energy trackingblocks 204 and 206. The control circuit 201 will be explained in moredetail later in the specification.

In buck energy transfer block 204, one terminal of inductor L1 iscoupled to a first switched transistor SW1 a, a second switchedtransistor SW1 b and to the cathode of diode D1. The other terminal ofthe inductor L1 is coupled to the output of the energy transfer block204. The anode of the diode D1 and a terminal of the second switchedtransistor SW1 b are connected to ground. A terminal of the firstswitched transistor SW1 a is connected to the input of buck energytransfer block 204. The switched transistors SW1 a and SW1 b can bereferred to as energizing switches. The diode D1 may be replaced orcomplemented by the second switch SW1 b. The control circuit 201controls the energy switches SWS1 a and SWS1 b. The control circuit 201will be explained in more detail later in the specification.

In buck energy transfer block 206, one terminal of inductor Li iscoupled to a first switched transistor SWia, a second switchedtransistor SWib and to the cathode of diode Di. The other terminal ofthe inductor Li is coupled to the output of the energy transfer block206. The anode of the diode Di and a terminal of the second switchedtransistor SWib are connected to ground. A terminal of the firstswitched transistor SWia is connected to the input of buck energytransfer block 206. The switched transistors SWia and SWib can bereferred to as energizing switches. The diode Di may be replaced orcomplemented by the second switch SWib. The control circuit 201 controlsthe energy switches SWSia and SWSib. The control circuit 201 will beexplained in more detail later in the specification.

FIG. 2b shows a simplified diagram of an embodiment of the invention. Inthis embodiment, an energy tracking system 200 comprises energy transferblocks 209, 211, a control circuit 201 and reference impedance 205. Inthis embodiment of the invention, energy transfer blocks 209 and 211 are“boost-buck” circuits. In this example two boost-buck energy transferblocks 209 and 211 are shown. However, more than two boost-buck energytransfer blocks may be used.

In boost energy transfer block 209, one terminal of inductor L1 a iscoupled to a first switched transistor SW1 a, a second switchedtransistor SW1 b and to the anode of diode D1 a. The other terminal ofthe inductor L1 a is coupled to an input of the energy transfer block209. The cathode of the diode D1 a, a terminal of the capacitor C1 a, aterminal of the second switched transistor SW1 b and a terminal of thethird switched transistor SW1 c are connected together. A terminal ofthe capacitor C1 a, a terminal of the first switched transistor SW1 a,the anode of diode D1 b and a terminal of the fourth switched transistorSW1 d are connected to ground. A terminal of inductor L1 b is coupled toa terminal of the third switched transistor SW1 c, a terminal of thefourth switched transistor SW1 d and to the cathode of diode D1 b. Theother terminal of the inductor L1 b is coupled to the output of theenergy transfer block 209. The switched transistors SWS1 a, SWS1 b, SWS1ic and SWS1 d can be referred to as energizing switches. The diode D1 amay be replaced or complemented by the second switch SW1 b. The diode D1b may be replaced or complemented by the fourth switch SW1 d. Thecontrol circuit 201 controls the energy switches SWS1 a, SWS1 b, SWS1 cand SWS1 d. The control circuit 201 will be explained in more detaillater in the specification.

In boost energy transfer block 211, one terminal of inductor Lia iscoupled to a first switched transistor SWia, a second switchedtransistor SWib and to the anode of diode Dia. The other terminal of theinductor Lia is coupled to an input of the energy transfer block 211.The cathode of the diode Dia, a terminal of the capacitor Cia, aterminal of the second switched transistor SWib and a terminal of thethird switched transistor SWic are connected together. A terminal of thecapacitor Cia, a terminal of the first switched transistor SWia, theanode of diode Dib and a terminal of the fourth switched transistor SWidare connected to ground. A terminal of inductor Lib is coupled to aterminal of the third switched transistor SWic, a terminal of the fourthswitched transistor SWid and to the cathode of diode Dib. The otherterminal of the inductor Lib is coupled to the output of the energytransfer block 209. The switched transistors SWSia, SWSib, SWSic andSWSid can be referred to as energizing switches. The diode Dia may bereplaced or complemented by the second switch SWib. The diode Dib may bereplaced or complemented by the fourth switch SWid. The control circuit201 controls the energy switches SWSia, SWSib, SWSic and SWSid. Thecontrol circuit 201 will be explained in more detail later in thespecification.

FIG. 3 shows the timing diagram for an energy transfer circuit (shown inFIG. 2a ) that has two transfer paths. The first path has SW1 a, L1, D1,and the ON-time signal SWS1 a applied to SW1 a. The switch SW1 b shownin energy transfer block 204, in this example, is not used. The secondpath has SWia, Li, Di, and the ON-time signal SWSia applied to SWia. Theswitch SWSib shown in energy transfer block 206, in this example, is notused. The two energy transfer paths are used mainly to enhance thedynamic range of delivering energy. The optional switches SW1 b and SWibmay be used to conduct current during the OFF-time to support thetransfer of energy from the inductors to the output. The optionalswitches SW1 b and SWib do not conduct energy after the energy transferis completed preventing that energy from flowing back from the output tothe input. The system may have more than 2 paths enabling further spreadof the dynamic range of the energy tracking circuits.

FIG. 4 shows more detail in the control circuit 201. The comparecircuits 406 and 434 are coupled to receive a reference signal VL(ref)that is used to determine the output voltages VL and V1. The output ofthe compare circuits 406 and 423 are coupled to the control logic stagesCNTLA 432, CNTL1 402 and CNTLi 404. The ON-time and OFF-time generator408 is coupled to feed the ON-time signals TG1 and TGi to the controllogic CNTL1 and CNTLi respectively. The control logic stage CNTLAprovides switching signals SWSA and SWSB for switching the switchingelement SWA and SWB to generate the voltage V1. The control logic stageCNTL1 provides switching signals SWS1 a and SWS1 b with constant widthON-time pulses for switching the switching element SW1 a and SW1 b. Thecontrol logic stage CNTLi provides switching signals SWS1 ia and SWSibwith constant width ON-time pulses for switching the switching elementSWia and SWib.

Issuing the next ON-time pulses is a function of the output signal 426of the compare circuit 406 and the ON/OFF-time. The constant widthON-time is generated in this embodiment from constant clock CLK (e.g.from a crystal oscillator). Such an implementation eases the calibrationsituation since the ON-time is nearly independent of the voltage andtemperature conditions. The primary side of the energy tracking systemis coupled to a first capacitor C1. Accordingly, one side of theinductor LA is coupled to one side of the first capacitor CA. The otherside of the first capacitor CA is coupled to ground. The primary side ofthe energy tracking system is supplied by a stable supply realized bythe circuit 202. The output or secondary side of the energy trackingsystem is coupled to a second capacitor C2 for buffering the outputvoltage VO. A target board or device under test 208 can be coupled tothe output of the energy tracking system. The current consumed by thetarget board or device under test is the load current IL The level ofthe output voltage is VO.

One or more reference impedances 205 in the form of reference resistor Rand a switch LS can be coupled through switch LS to the energy trackingsystem. Instead of the target board the reference resistor R can beswitched to the output VO. However, the target board or DUT may still becoupled to the output during the reference measurement. The result ofthe reference measurement with the well characterized reference resistorR can then be used to calibrate the measurement for the operation withthe unknown load (e.g. C3 & Z) of the target board 208. The energytransferred through the switched transistors SW1 and SWi during anON-time pulse is usually much smaller than the stored on the capacitorsCA and C2. If the energy that is transferred during an ON-time pulse isESW, the energy on capacitor CA is ECA, the energy on capacitor C1 isEC1, and the energy on capacitor C2 is EC2, the following advantageousratios are adventurous:

EC1=k1*ESWA

and

ECA=k2*(ESW1+ . . . ESWi)

-   -   where X={1 . . . i}

and

EC2=k3*(ESW1+ . . . ESWi)

-   -   where X={1 . . . i}

with

-   -   k1>20, k2 and k3>50.

ESWA and the sum of ESW1 to ESWi are much smaller than EC1, ECA and EC2.When the output voltage VO has settled, the compare block 426 measuresany deviation of target output voltage VL and versus VL(ref). Thecontrol blocks CNTL1 and CNTLi increase or decrease the density ofON-time pulses. The ON-time pulses are generated with a constant widthON-time and a minimum OFF-time. The inductors L1, and Li will be chargedwith a certain amount of energy from the second capacitor CA. During theOFF-time the energy in the inductors is transferred to the thirdcapacitor C2. In an embodiment of the invention, the second capacitor CAand the third capacitor C2 are sized such that this energy transfer doesnot significantly change the voltages across the second capacitor CA andthe third capacitor C2.

As long as the energy in the third capacitor C2 is sufficient tomaintain the output voltage VO, the compare block will not requestanother ON-time pulse through switching signal SWS1 a, SWS1 b or SWSia,SWSib. However, if a certain load current IL is consumed by the targetboard or DUT, the voltage across the second capacitor C2 is reduceduntil the voltage compare block VL=VL(ref) determines that the outputvoltage VO at output node OUT is lower than defined and generates arequest signal to CNTL1 and CNTLi. Another ON-time pulse will then begenerated. During normal operation, this causes a pulse density ofON-time pulses of signals SWS1 a and SWSia that is proportional to theconsumed energy of the DUT/target board 208. In another embodiment, thenumber of ON-time pulses per time counted by the accumulator 430 and thecurrent data there reflects and indicates the energy consumption. Understable input voltage conditions, each ON-time pulse representsapproximately the same amount of energy that is transferred during eachON-time pulse. The OFF-time variations of the ON-time pulses of theswitching signal SWSi1 and SWSia also indicate current variations of theload currents IL.

A reference measurement on the known reference resistor R can be usedfor normalizing the measured current. The reference resistors R may beswitched on through switch LS in addition to the target board 208. Theinfluence of the reference resistor R on the OFF-time in signals SWS1 aand SWSia can then be evaluated. However, the achieved result can beimproved if the reference resistor R is switched on while the targetboard is not connected.

FIG. 3 shows a diagram with waveforms of the load current IL, the outputvoltage VO, and ON-time signals as applied to switches SW1 a and SWS2 a.The load current IL of the target or DUT increases at a certain point oftime. The voltage VO at the output node OUT varies according to a sawtooth scheme around the target output voltage level. The pulse densityof the ON-time pulses SWS1 a and SWS2 a increases at a certain point oftime or starts (SWS2 a) depending on the extent of the load current IL.The voltage VO varies according to a saw tooth scheme around the targetoutput voltage level (dashed line). The pulse density of the ON-timepulses increases after the load current IL increases. This change indensity of ON-time pulses of both paths is evaluated.

Although the invention has been described hereinabove with reference toa specific embodiments, it is not limited to these embodiment and nodoubt further alternatives will occur to the skilled person that liewithin the scope of the invention as claimed.

1. An electronic device comprising an energy tracking system, the energy tracking system comprising a boost block, at least one energy transfer block and a control circuit wherein the control circuit is configured to control switching of energy in the first and second energy transfer blocks in order to transfer energy from a primary voltage applied at an input of the energy tracking system into a secondary voltage at the output of the energy tracking system; wherein the control circuit comprises an ON-time and OFF-time generator, at least one control logic block and an accumulator wherein the at least one control logic block is coupled to receive a signal from the ON-time and OFF-time generator and to generate switching signals for the first and second energy transfer blocks in the form of ON-time pulses with a constant width ON-time, and wherein the accumulator is configured to collect the number of ON-time pulses for determining the consumed energy based on the number of ON-time pulses per time; wherein the boost block comprises: a first inductor having a first terminal and a second terminal wherein the first terminal is connected to an input of the boost block; a first switching element, the first switching element being connected to the second terminal of the first inductor, to ground and to the control circuit; a first diode having a cathode and an anode wherein the anode is connected to the second terminal of the first inductor and the cathode is connected to an output of the boost block; a second switching element, the second switching element being connected to the second terminal of the first inductor, to the output of the boost block and to the control circuit; and a capacitor having a first terminal and a second terminal, the first terminal being connected to the cathode of the first diode and the second terminal of the capacitor being connected to ground. wherein the at least one energy transfer block comprises: a third switching element, the third switching element being connected to the control circuit, to the input of the at least one energy transfer block; a second inductor having a first terminal and a second terminal wherein the first terminal is connected to the third switching device and to an output of the at least one energy transfer block; a second diode having a cathode and an anode wherein the anode is connected to ground and the cathode is connected to the first terminal of the second inductor; a fourth switching element, the fourth switching element being connected to the control circuit, to the cathode of the second diode and the anode of the second diode.
 2. The electronic device of claim 1 wherein a second capacitor is connected to the input of the energy tracking system.
 3. The electronic device of claim 2 wherein a third capacitor is connected to the output of the energy tracking system.
 4. The electronic device of claim 1 wherein impedance is connected to the output of the energy tracking system. 